Hydrocarbon oil sweetening process



United States Patent OfiFice 3,130,149 Patented Apr. 21, 1964 3,13%,149 HYDRQCAREQN 03L SWEETENING PRQQEfiS Charles @scar Hoover, 5&2 Princess Drive, Corpus (:illifi, Tax. No Drawing. Filed Feb. 26, 1952, er. No. 175,831 15 6123315. (fill. Zed-4&4)

This invention relates to an improved process for sweetening hydrocarbon oils, such as petroleum oils.

sweetening, as that term is commonly employed in the petroleum industry, refers, in general, to treatment of petroleum oils, generally distillates, by processes which will convert mercaptans contained in the oil to the corresponding disulfides. The sweetening processes most comrnonly used in the petroleum industry, are treatment with lead plumbite or Doctor; treatment with cupric chloride; and in some instances with sodium hydroxide and oxygen. All of these are subject to numerous disadvantages. In the case of the Doctor and the sodium hydroxide processes, free sulfur must be added to complete the reactions and this addition of sulfur often renders the oil corrosive to copper by the standard test procedures and, therefore, undesirable. Moreover, the addition of free sulfur has a deleterious effect on the octane value of gasoline stocks and on its lead susceptibility.

In the case of cupiic chloride sweetening, the highly corrosive character of the reagent and the produced hydrochloric acid make the process objectionable in many instances. Also the treated oils are frequently unstable and lose color in storage.

Finally and most important, there are many petroleum stocks which cannot be sweetened completely by any of these conventional methods, that is, they all exhibit varying degrees of sourness to the standard Doctor test. Such resistant stocks, therefore, require highly special zed procedures to effect complete sweetening, and such procedures are usually relatively uneconomic.

It is a primary object, therefore, of this invention to provide a hydrocarbon oil sweetening process which avoids the various disadvantages of existing processes; is applicable to an exceptionally wide variety of petroleum stocks; is exceptionally low in cost; and is unusually simple to use.

In its broadest aspects, the present invention comprises the liquid phase treatment of mercaptan-containing hydrocarbon oils with two primary reagents, namely, an organic sulfonyl halide and an alkaline material exhibiting the properties of a strong base. The alkaline material may be admixed with the hydrocarbon oil stock either before or after the admixture of the sulfonyl halide with the oil, or may be otherwise contacted with the sulfonyl halide-containing oil.

The reaction takes place readily at ordinary temperatures and with equally successful results within the range of from about 40 F. to about 140 F.

Treatment by the process in accordance with this invention has been successfully applied to stocks obtained from Mexican, California, Kansas, West Texas and Gulf Coast crude oils, by straight run distillation, thermal cracking and catalytic cracking; ranging from straight gasolines and pressure distillates, kerosenes and burning oils, to heavy gas oils; and containing from 0.001 to 0.1 percent by weight of merctaptan sulfur.

The organic sulfonyl halide employed in the process of the present invention may be any compound of the general formula: RSO X where R is an alkyl or aryl nucleus and X is a halogen. The alkyl nucleus may be any straight or branched chain having two or more carbon atoms, some examples of which are enthanesulfonyl chloride, propane sulfonyl chloride, butane sulfonyl chloride, and the chain may be halogen substituted, as for example, trichlormethane sulfonyl chloride.

The aryl nucleus may be mono-cyclic or polycyclic and may be substituted, as with short alkyl groups, such as methyl, ethyl, etc., or may have other substitueuts. Examples of suitable aryl sulfonyl halides include the following: benzene sulfonyl chloride, p-toluene sulfonyl chloride, Z-naphthalene sulfonyl chloride, p-fluorobenzene sulfonyl chloride, 2,5-dichlorobenzene sulfonyl chloride, and p-bromobenzene sulfonyl chloride.

Although the number of available compounds usable in accordance with the present invention is exceptionally large, as noted, the particular reagent selected will be governed primarily by economic considerations of price and commercial availability; by efiiciency from the standpoint of reactivity; and by its capacity for use at normal temperatures and pressures.

In view of these considerations, benzene sulfonyl chlo ride and p-toluene sulfonyl chloride have been found most desirable for use in accordance with this invention.

The alkaline materials which are effective reagents in the present sweetening process include any of the many compounds which exhibit the characteristics of a strong base. These include the alkali metal hydroxides, the quaternary ammonium hydroxides, sodium aluminate, sodalime and the like. Also ion-exchange resins having strongbase characteristics are found to be functionally efiective in the present process. Sodium hydroxide is generally preferred for its cheapness, availability, and its reaction 'efiiciency particularly at normal temperatures and pressures.

The treating procedure is exceptionally simple, involving merely the mixing of each reagent with the oil to be treated and agitation for a short period of time. The sulfonyl halides, particularly the preferred p-toluene sul fonyl chloride or benzene sulfonyl chloride, being oil soluble, may first be dissolved in a suitable organic solvent, which will usually be the stock which is being tre-at ed. The quantity of the sulfonyl halide employed will be stoichiometrically related to the quantity of mercaptan present in the raw stock, being generally at least onehalf mol of the halide per mol of mercaptan. In many instances, some excess of the halide, for example, one mol or more per mol of mercaptan may be employed.

The alkaline reagent will generally be in the form of a water solution, and may be added to the oil either before or subsequent to the addition of the sulfonyl halide. Various concentrations of sodium hydroxide, for example, may be employed, ranging from as little as 1% concentration to as much as 4550% concentration. In general, that concentration will be selected which will give the quickest and most complete separation or break from the oil stock after completion of the treatment, and which is otherwise relatively free of mechanical difiiculties in use. The alkaline reagent may also be stoichiometrically related to the mercaptan, being generally at least one mol per mol of mercaptan. Volumetrically, the quantity of alkaline reagent will be such as to assure thorough contact and ready separation, and in general, will be at least 5% by volume of the oil.

In some cases, the sulfonyl-halide treated oil may be percolated through or otherwise contacted with a solid alkaline reagent, such as soda-lime or sodium aluminate, such reagents being entirely effective for completing the sweetem'ng reaction.

Amberlyst XNlOO2, the hydroxyl form of a strong base ion-exchange resin, manufactured by Rohm & Haas, is another example of a solid contact material which is functionally effective as an alkaline reagent for the present process.

Still other alkaline reagents which are found to be effective for the purposes of this invention are the alkali solutions of various lead compounds, particularly lead plumbite, commonly employed in Doctor sweetening of petroleum and made by dissolving lead oic'de or litharge in water solutions of sodium hydroxide; lead chloride; and lead sulfate.

The following Table 1 lists data on the effect of various organic sulfonyl halides on a sample of heavy petroleum naphtha containing 0.054% sulfur as mercaptan. Each reagent was added to the oil in 0.5 and 1.0 mol ratios per mol of mercaptan sulfur and thoroughly mixed. Each sample was then scrubbed with by volume of 45% soduim hydroxide solution for two minutes, and the treated oil separated from the mixture.

Table I Product '1 est Reagent Percent S as R-SH Doctor O. 002 Nil Nil Nil Pos...

None A lkyl Suli'onyl Halides:

Ethane sulfonyl chloride- Pos.

Do Buttiipe sulfonyl chloride 0 Triehloromethene sulfonyl ch1oride O Aryl Sulionyl Halides:

Benzene sulfonyl chloride p-toluene sulfonyl chloride. 0

2-napDhthalene sulfonyl chlo br mbiieiiz'fl'siiirbhri hh loride Although the reactions involved are not fully understood or determined, experience with the process of the present invention suggests that the principal reactions occur in two steps, as follows:

(I) alkaline R SOZ X RSH solution mercaptan sulfonyl thio-ester oi hall e halide t sulionic acid sal mercaptan disulfide Sulfinic acid salt thin-ester 0t sulfonic acid where R and R are alkyl or aryl groups; X is halogen and M is alkali metal or its functional equivalent.

The conversion of the mercaptan to disulfide renders the oil sweet to the standard Doctor test, the disulfide remaining dissolved in the oil. The alkali solution separates readily from the oil by stratification and will contain the sulfinic acid salt which is soluble in the aqueous alkali solution. The sulfonyl halide may be easily regenerated by contact with a suitable halide, for example, by bubbling chlorine gas, at atmospheric temperatures, through the alkali solution containing the sulfinic acid salt, the reaction being as follows:

As the sulfonyl halide is insoluble in aqueous solutions, it precipitates, as formed, and may be readily separated and recovered for re-use in the process, thereby rendering the process exceptionally economic.

Viewed from another aspect, the use of the sulfonyl halide in many instances, corresponds in function to the addition of free sulfur in conventional Doctor sweetening. As indicated previously, the alkali e reagent may be lead 'plumbite. This material may be admixed with the 'oil just as in the conventional Doctor sweetening. Thereupon, addition of a sulfonyl halide in the proportions mentioned will complete the mercaptan-conv-ersion reactions exactly as when adding free sulfur to sodium plumbite-treated oil.

The products obtained by the process in accordance with this invention, will be sweet to the Doctor test, will have good odor and color, excellent storage and oxidation stability, and improved lead response and neutralization value. 7

From the foregoing, it will be evident that the process in accordance with this invention provides a highly effective, simple and low cost process for sweetening hydrocarbon oils.

Other variations and modifications of the details of this invention will be apparent to those skilled in the art within the scope of the appended claims without departing from the spirit of this invention.

What I claim is:

1. The process for sweetening hydrocarbon oils, comprising, admixing With a mercaptan-containing hydrocarbon oil stock in the liquid phase an organic sulfonyl halide, contacting the admixture with an alkaline reagent exhibiting the characteristics of a strong base, and separating the treated oil from the admixture.

2. The process according to claim 1 wherein said organic sulfonyl halide is a member of the class consisting of benzene sulfonyl chloride, p-toluene sulfonyl chloride.

3. The process according to claim 1 wherein said alkaline reagent is an aqueous solution of sodium hydroxide.

4. The process according to claim drocarbon oil stock is a kerosene stock.

5. The process according to claim 1 wherein said or ganic sulfonyl halide is admixed with said oil stock in the proportions of at least one-half mol of the sulfonyl halide per mol of mercaptan sulfur in said oil stock.

6. The process for sweetening hydrocarbon oils, comprising, admixing with a mercaptan-containing hydrocarbon oil stock in the liquid phase an oil-soluble organic sulfonyl halide having the general formula: RSO X, wherein R is a group selected from the class consisting of alkyl and aryl, and X is a halogen, contacting the admixture with an alkaline reagent exhibiting the characteristics of a strong base, and separating the treated oil stock from the admixture.

7. The process for sweetening hydrocarbon oils, comprising, admixing With a mercaptan-containing hydrocarbon oil stock in the liquid phase an oil-soluble organic sulfonyl halide having the general formula: RSO X wherein R is a group selected from the class consisting of alkyl and aryl, and X is a halogen, contacting the admixture with an aqueous solution of an alkali hydroxide, and separating the treated oil from the alkali solution.

8. The process for sweetering hydrocarbon oils, comprising, admixing with a mercaptan-containing hydrocarbon oil stock in the liquid phase an oil-soluble organic sulfonyl halide having the general formula: RSO X wherein R is a group selected from the class consisting of alkyl and aryl, and X is a halogen, contacting the admixture with an aqueous solution of an alkali hydroxide, separating the treated oil from the alkali solution, treating the alkali solution with a source of said halide under conditions to regenerate the sulfonyl halide, and recovering the sulfonyl halide.

9. The process for sweetening hydrocarbon oils, comprising, admixing with a mercaptan-containing hydrocarbon oil stock in the liquid phase p-toluene sulfonyl chloride in the proportions of at least 0.5 mol per mol of mercaptan sulfur in the oil stock, contacting the admixture with aqueous solution of an alkali hydroxide fora time suflicient to sweeten said oil stock, and separating the treated oil stock from the admixture.

10. The process according to claim 9 wherein said bydrocarbon oil stock is a kerosene stock.

11. The process according to claim 9 wherein said alkali hydroxide is sodium hydroxide in a concentration of from about 1% to about 50% NaOH by Weight of said 1 wherein said hysolution, and in the proportion of at least one mol of NaOH per mol of mercaptan sulfur in said oil stock.

12. The process for sweetening hydrocarbon oils, comprising, admixing with a mercaptan-containing hydrocarbon oil stock in the liquid phase benzene sulfonyl chloride in the proportion of at least 0.5 mol per mol of mercaptan sulfur in the oil stock, contacting the admixture with an aqueous solution of sodium hydroxide, and separating the treated oil stock from the admixture.

13. The process according to claim 12 wherein said hydrocarbon oil stock is a kerosene stock.

14. The process according to claim 12 wherein the sc lution of sodium hydroxide contains from about 1% to about 50% by weight of NaOH and wherein the quantity of said solution is such as to provide at least one mol of NaOH per mol of mercaptan sulfur in the oil stock.

15. The process for sweetening hydrocarbon oils, comprising, successively admixing with a mercaptan-containing hydrocarbon oil stock in the liquid phase an organic sulfonyl halide, and an alkaline reagent exhibiting the characteristics of a strong base, the additions of the reagents being made in any order, and separating the treated oil from the resultant mixture.

16. The process for sweetening hydrocarbon oils, comprising, successively admixing an organic sulfonyl halide with a mercaptan-containing hydrocarbon oil stock in the liquid phase in the presence of an alkaline reagent exhibiting the characteristics of a strong base, and separating the treated oil from the resultant mixture.

No references cited. 

1. THE PROCESS FOR SWEETENING HYDROCARBON OILS, COMPRISING, ADMIXING WITH A MERCAPTAN-CONTAINING HYDROCARBON OIL STOCK IN THE LIQUID PHASE AN ORGANIC SULFONYL HALIDE, CONTACTING THE ADMIXTURE WITH AN ALKALINE REAGENT EXHIBITING THE CHARACTERISTICS OF STRONG BASE, AND SEPARATING THE TREATED OIL FROM THE ADMIXTURE. 